A straightforward way to reduce emissions is to get rid of your car--and that's exactly what some Americans appear to be doing.
Consulting firm Alix Partners released a report that claims car-sharing services have eliminated 500,000 sales of new cars.
The researchers claim that automakers have underestimated the popularity of car sharing, which allows members to rent cars on a short-term basis.
Car-sharing operations like Zipcar give drivers relatively unfettered access to vehicles without any driver actually having to own one.
If the trend continues, Alix Partners claims, car-sharing could eliminate a total of 1.2 million car sales by 2021.
Zipcar will add the 2012 Ford Focus to its college car-sharing locations
Driving less, sharing more
The car-sharing study is the latest to show that Americans are less interested in car ownership than they have been in past decades.
A study released by the American Association of State Highway and Transportation Officials last October notes that the number of "Zero-Car Families" in the U.S. is on the rise.
Researchers identified an increase in the number of American households without a car, the first time the phenomenon had been seen in decades.
In addition, the Federal Highway Administration has found that annual per-capita Vehicle Miles Traveled (VMT) peaked in 2004 and have declined steadily since then.
Cars in decline?
The Alix Partners study focused on 10 urban markets, where more consumers presumably have the option of taking mass transit, walking, or even biking to their destinations.
Access to alternative forms of transportation is thought to be one of the reasons why young people are driving much less, along with the high cost of car ownership, higher environmental consciousness, and the omnipresent smartphone.
Advances in communication technology have also made it possible for more people to work from home.
Still, people use cars for things other than commuting, and not everyone lives in a city.
The suburban infrastructure built up since World War II means that most U.S. families and individuals will still require at least one vehicle well into the future.